Method of making structured protein compositions

ABSTRACT

An extrusion process is disclosed for turning vegetable protein compositions such as soy protein into a fibrous, meat-like structure. The process involves the application of relatively high moisture contents. An open structure is produced that can be infused with water so as to influence the product&#39;s tenderness. The products of the invention can be provided with a fibrosity and tenderness at will. The invention offers the possibility to include relatively high amounts of fat in the product.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. Non-Provisional patentapplication Ser. No. 14/116,860 filed Dec. 30, 2013, which is a NationalPhase of PCT/NL2012/050320 filed May 10, 2012, which claims priority toEP No. 11166038.7 filed May 13, 2011, the disclosures of which areincorporated by reference herein.

FIELD OF THE INVENTION

The invention pertains to an extrusion process for making structuredvegetable protein compositions, particularly compositions having afibrous meat-like structure. The invention further pertains to meat-likecompositions having a high water-absorption capacity and to the use ofvegetable protein in making a range of edible products comprisingdifferent meat-like structures.

BACKGROUND TO THE INVENTION

It is well-known to use vegetable protein sources as a replacement foranimal protein, including meat. This is widely used so as to provide thenecessary proteins in a vegetarian diet. During the past decade,attention has increasingly emerged on reducing the consumption of meat.This has various backgrounds, depending on, e.g., the region of theworld, including health benefits, meat scarcity, and social andenvironmental desires, such as animal welfare and reducing the effectsof meat-production for the release of CO₂ into the environment.

A major limitation to attempts to reduce the consumption of meat is thegeneral acceptability of vegetable protein products asmeat-replacements. In order for these products to be generally accepted,it is considered that such meat-replacement should actually resemblemeat. Although many different products exist on the basis of, e.g.,soy-bean protein that are claimed to resemble meat, these products tomany consumers are still not sufficiently alike meat to really count asan acceptable replacement

The main route in the art in providing acceptable meat-replacements isto try and provide a meat-like fibrous structure. A further desire is toprovide a process by which a range of meat-replacements can be producedon the basis of vegetable protein. For, it makes quite a differencewhether the structure is produced as a replacement for minced meat, forchicken, pork steak, or for beef. A largely unmet desire is to provide aprocess that is capable of producing vegetable protein-based analoguesof the more challenging meat structures, such as pork steak or beef. Aparticular further desire is to provide a process that is capable ofbeing tuned towards the production of any one of a variety of meatreplacements, ranging from minced meat to ham, chicken, or beef.

Several references address the production of fibrous, sometimesmeat-like protein structures.

WO 03/07729 concerns a method of continuously preparing a retexturedfood product from a protein-rich raw material of animal and/or plantorigin. In an extruder the raw material is subjected to mixing, cooking,and plasticizing steps, and cooled gradually in an extrusion die to atemperature that preferably is 40° C. to 80° C. In general products areobtained having a longitudinal fibrous structure. Such a structure isnot generally acknowledged as being meat-like. To the extent thatmeat-like structures are suggested, this refers to a fibrous sheetstructure. Whilst said to be a approximation of poultry meat, this is arelative simplification of such meat.

WO 2009/105654 relates to a protein composition for meat products ormeat analogue products. The composition is granular, and is prepared bya process involving making a hard fibrous gel, and reducing the sizethereof to particles of about 2 mm to 10 mm particle size. In someembodiments, granules are mixed with aligned protein fibres, and thenchopped. The process of making the aligned protein fibres can beconducted by extrusion. To this end an extrusion die is used that servesto align fibres.

In any event, the resulting chopped structure does not resemble afibrous muscle meat, and the process requiring fibre alignment resultsin a simplification of a meat structure. Moreover, the process does notprovide the versatility to produce meat analogues ranging from mincedmeat analogues to steak analogues.

A general background reference on protein structuring is Cheftel et al.,Food Reviews International 8(2), 235-275 (1992). Herein a proteintexturization process is described, involving extrusion cooking at highmoisture levels. The document relates to a broad range of products. E.g.it is described how fish proteins are restructured, how cheese-likeproducts can be made, and how extrusion cooking can be used to createfat substitutes. It will be appreciated that the disclosed structuresare not at all alike meat of land-animals.

The background art further includes U.S. Pat. No. 4,276,319. Therein theproduction of a dense, granulated protein gel is disclosed which, uponrehydration, is to function as a meat extender in natural meat products.The disclosure does not provide a meat analogue of a meat-like structurethat would be suitable per se as a meat replacement, rather than as anextender.

Yet another background reference is Kitabatake, Journal of Food Sciencevol. 50, 1985, pages 1260-1264. Therein the production of gels from soyprotein isolate is disclosed. The disclosure is not directed to makingmeat-analogues, and the disclosed gels do not satisfy the correspondingtexture requirements.

SUMMARY OF THE INVENTION

In order to better address the foregoing and other desires, theinvention, in one aspect, presents a process for the preparation of astructured vegetable protein extrudate, comprising the steps of

-   -   (a) providing an aqueous protein composition comprising        vegetable protein, wherein the protein content based on dry        matter is below 90% by weight;    -   (b) subjecting the aqueous protein composition to one or more        kneading steps so as to form a dough;    -   (c) subjecting the dough to heating to above the denaturation        temperature of the protein;    -   (d) subjecting the dough to shear forces and pressure in an        extruder, so as to form a fibrous protein composition;    -   (e) allowing the fibrous protein composition to exit the        extruder through an extruder die;        wherein the water content of the aqueous protein composition is        at least 50% by weight, and wherein fibrous protein composition        is subjected to limited cooling so as to exit the extruder at a        temperature, of the composition, of at least the boiling        temperature of water in said first outside environment.

In another aspect, the invention is a process for the preparation of astructured vegetable protein composition, wherein a structured vegetableprotein extrudate is made by a method as described above, and whereinthe extrudate is subjected to infusion by an aqueous liquid.

In a still further aspect, the invention provides the use of a method asdescribed above for the production of a range of meat-like structures,wherein the choice of one or more temperature values in step (c) is usedas a tool to determine the desired fibrosity, and the water contentintroduced by the infusion with the aqueous liquid is used to determinethe desired tenderness.

In another aspect, the invention presents a structured vegetable proteinproduct comprising 0.1-20 wt. % of fat, preferably 0.2-10 wt. %.

In a still further aspect, the invention provides a structured vegetableprotein product obtainable by the aforementioned method, wherein theproduct satisfies a water-absorption capacity of at least 50% measuredin accordance with a test conducted as follows:

-   -   (a) providing a piece of the product of 50 g each;    -   (b) measuring the precise weight of the piece;    -   (c) submerging the piece separately in boiling water;    -   (d) keeping the piece in boiling water for 20 minutes;    -   (e) taking the piece out of the water and allowing it to drain        for 1 minute;    -   (f) measuring the weight of the drained piece;    -   (g) repeating steps (a)-(f) with 3 further pieces;    -   (h) determining the average weight of the four pieces at step        (b);    -   determining the average weight of the four pieces at step (f);    -   (j) subtracting the outcome of (h) from the outcome of (i) so as        to obtain the average weight increase as a measure for the        water-absorption capacity.

DETAILED DESCRIPTION OF THE INVENTION

In a broad sense, the invention is based on the judicious recognition tocombine the extrusion of a protein composition having a relatively highmoisture content with allowing the extrudate to exit the extruder at atemperature of at least the boiling temperature of water.

Thus, the invention presents a process for the preparation of astructured vegetable protein extrudate, comprising the steps of

-   -   (a) providing an aqueous protein composition comprising        vegetable protein;    -   (b) subjecting the aqueous protein composition to one or more        kneading steps so as to form a dough;    -   (c) subjecting the dough to heating to above the denaturation        temperature of the protein;    -   (d) subjecting the dough to shear forces and pressure in an        extruder, so as to form a fibrous protein composition;    -   (e) allowing the fibrous protein composition to exit the        extruder through an extruder die;        wherein the water content of the aqueous protein composition is        at least 50% by weight, and wherein fibrous protein composition        is subjected to limited cooling so as to exit the extruder at a        temperature, of the composition, of at least the boiling        temperature of water in said first outside environment.

Without wishing to be bound by theory, the inventors believe that theforegoing combination of features is responsible for the creation of arelatively open structure in the composition when it leaves theextruder. This open structure has an improved capability of beinginfused with an aqueous liquid, and thus presents a choice of creating alower or higher tenderness, dependent on the percentage of water thusadded.

The vegetable protein source preferably has a protein content of below90% by weight of the dry matter of the composition. This defines aprotein content essentially below that of protein compositionsrecognized in the art as “protein isolates”. Such lower protein contentcompositions have been found by the inventors to be unexpectedly bettersuitable to create meat-like structures.

For the sake of optimal processing into meat-like, fibrous structures,it is preferred that the protein content, based on dry matter of theprotein composition, is in a range of from 15% by weight to 85% byweight, and more preferably of from 35% by weight to 85% by weight.Still more preferably, said protein content is 50% by weight to 80% byweight. Most preferably, the protein content of the protein compositionsubjected to extrusion is 65% by weight to 75% by weight, again based ondry matter of the composition.

The fibrous composition obtained in the extruder, exits the extruder ata temperature, of the composition, higher than the applicable boilingtemperature of water (e.g. 100° C. at atmospheric pressure, or lower inthe event that a vacuum port is used). This is believed to result inexpansion and subsequent collapsing of the texturized product. Theexpansion/collapsing treatment is believed to disturb the fibreorientation and thus to result in the formation of a more randomorientation of the formed fibres. Next to that, it is believed to leadto formation of air pockets (on micro and macroscale) in the texturizedproduct.

To fine-tune mouth feel (bite), tenderness and juiciness the texturizingprocess can be followed by hydration of the extruded product in anaqueous liquid, at elevated temperatures, i.e. between 40 and 150° C.,until a final moisture content of 50 till 95% is reached. Shear bladetesting is most commonly used for measurement tenderness, for instanceWarner Bratzler shear blade or the Kramer shear cell.

The product of the invention has a heterogeneous structure and arelatively large free volume. This contributes to its relatively highwater-absorption capacity. This is of advantage, since the absorption ofaqueous liquids facilitates adding desired taste components, as well asallows to vary the product in terms of juiciness and bite.

The infusion of the extrudate according to the invention occurs on wetproduct as obtained by extrusion. In deviation from the background art,the extrudate of the present invention does not require drying andrehydration. It essentially remains wet, and is then further filled withwater, or another aqueous composition, by infusion. The extrudatepreferably has a water-content of 55% by weight to 70% by weight. Thestructured vegetable protein composition resulting from infusion with anaqueous liquid preferably has a water-content of from 70% by weight to90% by weight.

Surprisingly, the aforementioned infusion by an aqueous liquid can beimproved (i.e. proceeding more rapidly and/or allowing the incorporationof more water) if the extrudate has first been frozen (and then thawedprior to infusion). Preferably, the freezing temperature is below −5° C.and, more preferably below −15° C.

During extrusion, the composition is heated to a temperature above thedenaturation temperature of the protein. For soy bean protein this meansa temperature of at least 130° C. Preferably the extrusion is conductedat a temperature of at least 150° C. A preferred maximum temperature is200° C.

It will be understood that the process temperature can be lowered bymeasures to lower the protein's iso-electric point, e.g. by lowering pHand/or by the addition of proteases. It is preferred according to theinvention to produce as pure a protein product as possible, and thus theaddition of acid and/or protease is preferably avoided.

The term “structured vegetable protein product” implies that a productis provided comprising vegetable protein, wherein the vegetable proteinis comprised in a man-made structure. According to the invention, thisstructure is obtainable by the extrusion method referred to above.

A wide range of meat-like fibrous structures can be prepared. Thedesired structural properties are generally determined by the fibrosity(fibrousnesses) of the extrudate, and the aforementioned tenderness.Fibrosity, as is known to the skilled person, can best be determined bymeans of visual inspection of the extrudate itself, or of a photographthereof. If desired, the inspection can be done via a microscope. In anyevent, the determination amounts to a visual assessment, if needed usinga device to measure lengths, such as a graduated rod. In general ahigher degree of fibrosity (longer fibres) is obtained upon applying ahigher temperature during extrusion. A lower temperature will lead toshorter fibres. In general fibres of pork-like fibrous structure will beprepared at the lower end of the above mentioned temperature ranges, achicken-like fibrous structure will result from an intermediatetemperature, and a squid-like fibrosity will result from temperatures atthe high-end of the ranges. In connection herewith, the invention alsopertains to the use of a method as substantially described hereinbefore,for the production of a range of a meat-like fibrous structuredvegetable protein composition, wherein the choice of one or moretemperature values in step (c) is used as a tool to determine thedesired fibrosity. Temperature settings are a normal tool for theskilled person to influence the outcome of an extrusion process.However, it is a surprising achievement of the present invention thatthe adjustment of temperature has the effect of fine-tuning theextrudates' fibrosity. It should be noted that the invention, inaccordance with this aspect, is not limited to any specific value forfibrosity, but is directed to the fact that by the relatively simple actof adjusting temperature a wide range of products of any desiredfibrosity can be produced.

It should be noted that the process of the invention, in deviation fromthe standard approach in the art, does not aim at a structural imitationof the fibrous structure of the meat to be replaced. Surprisingly, theprocess of the invention results in a product having its own fibrousstructure, that is essentially capable of providing a “bite” that isperceived as being meat-like.

The process of the invention allows an as yet unachievable versatility,by the fact that not only the degree fibrosity can be tuned, as above,but independently also the degree of tenderness, as a small butsignificant percentage of the final water-content of the product isdetermined by the water added through the infusion step after extrusion.It will be appreciated that the range of temperatures (determining therange of fibrosity achievable), and the range of water percentages thatcan be incorporated into the structure (as a result of the opennesscreated upon exit at the extruder) present a great variety ofpermutations that enable the production of a more or less fibrous andmore or less tender product.

The present invention will further be described with respect toparticular embodiments. The invention is not limited thereto but only bythe claims. Where the term “comprising” is used in the presentdescription and claims, it does not exclude other elements or steps.Where an indefinite or definite article is used when referring to asingular noun e.g. “a” or “an”, “the”, this includes a plural of thatnoun unless something else is specifically stated.

The aforementioned extrusion process starts with providing a proteinfrom a vegetable source. Vegetable sources include plant sources,including algae. This protein can be from a mixture of sources, e.g. soybean protein, lupin protein, wheat protein. Preferably, protein sourcesdevoid of gluten are used. It is not excluded that proteins fromnon-vegetable sources are present in addition to the vegetable protein,including proteins from animal sources. This is not preferred, and oneif the advantages of the present invention is that a meat-perceptionstructure can be actually produced without using animal protein.

Preferred vegetable proteins are soy bean protein, more preferably soyprotein isolate or soy protein concentrate. Soy protein isolate is ahighly refined or purified form of soy protein with a minimum proteincontent of 90% on a moisture-free basis. It is made from defatted soyflour which has had most of the non-protein components, fats andcarbohydrates removed. Soy flour refers to a comminuted form of defattedsoybean material, preferably containing less than about 2% oil, formedof particles having a size such that the particles can pass through aNo. 100 mesh (U.S. Standard) screen. Soy protein concentrate is adefatted soy material having a protein content of from about 65% to lessthan about 90% soy protein on a moisture-free basis.

In providing meat-replacement it can be desired to include fat in thecomposition. This is generally difficult to achieve with existingprocesses. In the process of the invention, fat can be added to theproduct via the dough, via the infusion liquid, or both. An advantage ofthe method of the invention is that, particularly by virtue of the useof an infusion liquid, an amount of fat can be included (e.g. 0.1-20% byweight, preferably 0.2-10 wt. %, more preferably at least 5%), that itsubstantially higher than for pre-existing textured protein productsbased on vegetable protein. In this respect the invention, in oneaspect, also relates to a structured vegetable protein productobtainable by the aforementioned method, comprising 0.1-20 wt. % of fat,preferably 0.2-10 wt. % of fat. In one interesting embodiment, theamount of fat is 0.2-1 wt. %. In another interesting embodiment, theamount of fat is higher than 1 wt. % and up to 20 wt. %, preferably 5-10wt. %. The term “fat”, as used herein, serves to include fats, oils, andother lipids.

In accordance with the invention, an aqueous protein composition isprovided, the composition is subjected to kneading to form a dough, andthe dough (after heating) is subjected to shear and pressure in anextruder.

The process can be conducted by providing a first section of an extruderwith a protein from a vegetable source and water so as to form anaqueous protein composition; it can also be done by adding water in oneor more subsequent sections of the extruder, or in both in an initialsection and in one or more subsequent section. The aqueous proteincomposition can also be prepared in a separate premixing zone afterwhich it is provided to the extruder. The composition can also be in theform of a premixed dough that is pumped into the extruder.

An extruder generally comprises a plurality of temperature controlledzones or sections through which the protein product mixture is conveyedunder mechanical pressure prior to exiting the extrusion apparatusthrough an extrusion die assembly.

The skilled person is aware of suitable extrusion apparatuses. Theseare, e.g., a double barrel, twin-screw extruder as described, forexample, in U.S. Pat. No. 4,600,311. Further examples of suitablecommercially available extrusion apparatuses include a CLEXTRAL ModelBC-45, a CLEXTRAL Model BC-63 extruder manufactured by Clextral, Inc.(St Etienne France); a WENGER Model TX-57 extruder, a WENGER ModelTX-168 extruder, and a WENGER Model TX-52 extruder all manufactured byWenger Manufacturing, Inc. (Sabetha, Kans.), a BÜHLER BCTG-40 and aBÜHLER BCTG-62 both manufactured by Bühler AG (Uzwil, Switzerland).Other conventional extruders suitable for use in this invention aredescribed, for example, in U.S. Pat. Nos. 4,763,569, 4,118,164, and3,117,006.

It is preferred to use an extruder having a ratio of length:diameter(L/D) greater than 20, preferably greater than 30, and more preferablyhaving an L/D greater than 40. The upper limit is not critical for theinvention, and will be determined by practical or mechanicalconsiderations. A preferred upper limit is an L/D of 50. A higher L/D(preferably above 40) is particularly preferred if mixing water andprotein composition takes place in the extruder. The L/D canconveniently be about 10-15 lower (preferably still above 30). if themixing is done prior to entry into the extruder.

The extruder can be single screw but is preferably of the twin-screwtype. The screws of a twin-screw extruder can rotate within the barrelin the same or opposite directions. Rotation of the screws in the samedirection is referred to as single flow whereas rotation of the screwsin opposite directions is referred to as double flow. The speed of thescrew or screws of the extruder may vary depending on the particularapparatus; however, it is typically from about 50 to about 1500revolutions per minute (rpm). The extrusion apparatus contains screwsassembled from shafts and worm segments, as well as mixing lobe andring-type shear lock elements as recommended by the extrusion apparatusmanufacturer for extruding plant protein product.

A section of an extruder can either be visibly distinguishable as asub-part of an extruder, or it can be functionally be a sub-part (e.g.zones allowing different heating or cooling regimes can define differentsections).

The aforementioned first section preferably forms the entrance(introduction section) of the extruder.

In addition to protein, also water is provided to said first section.The protein and the water can be introduced into the extruder in anyorder, as long as in subsequent sections of the extruder the materialbeing extruded comprises an aqueous protein composition. E.g., theprotein and water can be premixed and then introduced into the extruder,or part of the protein and the water can be premixed and the remainedadded separately. Preferably, the protein and water starting materialsare provided separately, and are not mixed until their being introducedinto the extruder. More preferably, the stream or streams of protein anda stream of water are introduced substantially simultaneously into theextruder. The protein and the water are introduced preferably at atemperature below the denaturation temperature of the protein, and arepreferably not heated. The first section of the extruder also ispreferably neither heated nor cooled.

The aqueous protein composition as being extruded generally has a watercontent of at least 50 wt. %, more preferably at least 60 wt. %. Themaximum water-content should be such as to still allow the extruder toprovide a structure to the composition. The maximum water contentpreferably is 70 wt. %, more preferably 65 wt. %.

In one or more subsequent sections, the treatments of kneading, heating,and shearing the aqueous protein composition are conducted. Beforeand/or during these steps, the composition is heated to above thedenaturation temperature of the protein. In general, the kneading andheating will take place simultaneously, although it is conceivable tostart kneading before heating, or to not start kneading until afterdenaturation has occurred.

The kneading results in a dough that is subjected to shear forces andpressure. These forces are exerted in one or more sections and serve toprovide a microfiber structure. The absolute pressures and shear forcesused will differ per extruder type. The skilled person will be able totune these values without undue experimentation by simple inspection ofa few trial extrudates.

In a final section, just preceding the opening through which theextrudate leaves the extruder, the pressure is preferably lowered ascompared to the previous sections.

The aforesaid opening is provided in an extruder die assembly. Since theextruded mass is heated, it is desired that cooling is provided prior tothe extrudate exiting the extruder. This cooling can be done in asection prior to the die assembly, but preferably a so-called “coolingdie” is used. Such a die comprises a longitudinal section in whichcooling is provided, and the actual die, i.e. the opening to a firstenvironment outside of the extruder.

In an interesting embodiment, the extruder die is a sheet-type diehaving an opening the largest dimension of which is larger than thelength of the longitudinal section. This is a considerably change ascompared to regular cooling dies, which are relatively long. Taking thetwo dimensions of the opening (say: height and width), the smallerdimension (say the height) is preferably relatively small, e.g. onehundredth to one tenth of the larger dimension (i.e. the width). Theaforementioned longitudinal section of the die assembly (i.e. thesection directly preceding the opening) preferably has substantially thesame width and height dimensions as the opening.

Without wishing to be bound by theory, the inventors believe that theforegoing preferred die assembly contributes to obtaining a fibrousstructure that is not only provided in longitudinal direction, but alsoin other directions under an angle with the longitudinal fibres. Inother words, the die assembly (which is hardly or not used for itsregular purpose—cooling) is used in the invention to provide anorientation to the fibrosity. The lower die pressure, but combined withthe relatively high shear forces caused by the shape of the die, resultin a macrofiber, layered, structure that contributes to the favourablebite of the extrudate. Generally, a product is obtained having a doublefibrous structure, having larger fibres in one direction, and smallerfibres in a different direction.

Via the die, the extrudate enters into a first outside environment.Hereby the temperature of the composition is secured to be above theboiling point of water in said environment. It will be understood thatif, as preferred, the environment is at atmospheric pressure, theboiling point of water will be 100° C. It will also be understood thatthe temperature may be lower or higher depending on the exactatmospheric pressure. As a result, the extrudate will expand to someextent, on account of gaseous bubbles formed therein. These gaseousbubbles will result in cavities, i.e. an open structure, that can beaccommodated to take up water. It will be appreciated that this isdifferent from regular marinating or infusion. The addition of water, in0 wt. % to 100 wt. %, preferably 25 wt. % to 75 wt. % of the total watercontent, by virtue of the open structure created, provides a novel andjudicious way of determine the tenderness of the product obtained fromthe extrudate and, together with the fibrosity and preferably the doublefibrosity mentioned above, the meat-like character of the product.

As referred to above, the water uptake preferably is conducted through aprocess of infusion with an aqueous liquid. The aqueous liquid ispreferably heated, more preferably to a temperature of 50° C. to 100°C., more preferably 70° C. to 98° C. The aqueous liquid can be water. Asa matter of choice, the aqueous liquid can also be used to provide aflavour to the composition. To this end, the aqueous liquid preferablyis a broth. Depending on the intended end-use, stronger or softerflavours can be added.

In connection herewith, the invention, in another embodiment, alsopresents a process for the preparation of a meat analogue, wherein astructured vegetable protein extrudate is made by a method as describedabove, and wherein the extrudate is subjected to infusion by an aqueousliquid, preferably a heated liquid, and more preferably a broth.

As explained above, the possibilities to tune both the fibrosity and thetenderness enable the use of the process of the invention for themanufacture of a range of meat-like products on the basis of vegetableprotein.

In connection herewith, in yet another aspect, the invention providesthe use of a method as described above for the production of a range ofmeat-like structures, wherein the choice of one or more temperaturevalues in step (c) is used as a tool to determine the desired fibrosity,and the water content introduced by the infusion with the aqueous liquidis used to determine the desired tenderness.

In addition to allowing the tuning the fibrous structures as well as thetenderness of a structured vegetable protein product, the process of theinvention leads to a novel approach of providing meat-replacement. Thestructured vegetable protein product of the invention, by virtue of theextrusion and infusion process, is capable of providing the consumerwith a bite and mouth feel that gives the impression of meat, withoutnecessarily copying the actual fibrous structure of meat. The inventiontherewith also presents the identification of a technical problem thatis different from the way this has been addressed in the art. Thistechnical problem, rather than how to copy meat structures in astructured vegetable protein product, is how to provide a structurehaving a fibrous character and tenderness that is perceived by theconsumer as being meat-like.

The products of the invention are generally obtained as a continuousextrudate and can be cut to size at will. The resulting meat-likeproduct will be a semi-final article, that can be further processed bycutting, milling, or other techniques to produce desired shapes andsizes so as to produce an article that is ready for being processed by acook (e.g. by frying it, providing it with flavours or, in whicheverother way, incorporating it into a dish).

The invention will be illustrated with reference to the following,non-limiting Example.

Example

In this example, a Clextral BC45 twin-screw extruder is used for thepreparation of a structured composition on the basis of soy beanprotein. The extruder has a length of 150 cm and a length to diameter(L/D) ratio of 27. The extruder is divided into six sections of 25 cmeach. The first section is an introduction section that is not cooled orheated. The table below summarizes the processing in the varioussections.

Temp. Section ° C. Process 1 — 25 cm transport 2 80 25 cm transport andpressure building 3 150 20 cm transport, increasing pressure building, 5cm mixing 4 150 5 cm mixing, 20 cm transport and pressure reduction 5150 20 cm transport, 5 cm mixing 6 90 25 cm transport and pressureincrease

To the introduction section 8.4 kg/hr soy concentrate is added (the %protein of the concentrate is 69±3%) and 12.9 kg/hr water (using aplunger pump). The rotation rate of the extruder is 165 rpm. Theextruder is provided with a sheet-die having the dimensions: length 90mm, width 150 mm, and height 3.15 mm. By allowing water to flow throughthe sheet-die, the extrudate is cooled, but to a limited extent, viz. atemperature of between 100° C. and 120° C. The extrudate is subsequentlyinfused with water, or with a mixture of water and flavours.

1. A structured soy bean protein extrudate satisfying a water-absorptioncapacity of at least 50% measured in accordance with a test conducted asfollows: (a) providing a piece of the product of 50 g each; (b)measuring the precise weight of the piece; (c) submerging the pieceseparately in boiling water; (d) keeping the piece in boiling water for20 minutes; (e) taking the piece out of the water and allowing it todrain for 1 minute; (f) measuring the weight of the drained piece; (g)repeating steps (a)-(f) with 3 further pieces; (h) determining theaverage weight of the four pieces at step (b); (i) determining theaverage weight of the four pieces at step (f); (j) subtracting theoutcome of (h) from the outcome of (i) so as to obtain the averageweight increase as a measure for the water-absorption capacity.
 2. Theextrudate of claim 1, wherein the protein content based on dry matter isin a range of from 50% by weight to 80% by weight.
 3. The extrudate ofclaim 1, comprising 0.1-20 wt. % of fat.
 4. The extrudate of claim 1,comprising 0.2-10 wt. % of fat.
 5. A product comprising the extrudate ofclaim 1, infused with an aqueous liquid.
 6. The product of claim 5,obtained by first subjecting the structured soy protein extrudate tofreezing, and then allowing the frozen extrudate to thaw upon theinfusion.
 7. The product of claim 5, wherein the aqueous liquid is watercomprising flavours.
 8. The product of claim 5, wherein the aqueousliquid is a broth.
 9. A structured soy bean protein extrudate,obtainable by a process comprising the steps of: (a) providing anaqueous soy protein composition, wherein the protein content based ondry matter is at least 15% by weight and below 85% by weight; (b)subjecting the aqueous soy protein composition to one or more kneadingsteps so as to form a dough; (c) subjecting the dough to heating toabove the denaturation temperature of the protein; (d) subjecting thedough to shear forces and pressure in an extruder, so as to form afibrous soy protein composition; (e) allowing the fibrous soy proteincomposition to exit the extruder as an extrudate into a first outsideenvironment, whereby the extrudate enters said first outside environmentthrough an extruder die; wherein the fibrous soy protein composition issubjected to limited cooling such that the extrudate, upon exiting theextruder into said first outside environment, has a temperature of atleast the boiling temperature of water in said first outsideenvironment, thereby forming a cooled fibrous protein composition havingenhanced porosity and/or randomization of fiber orientation relative toa fibrous protein composition cooled to below the boiling temperature ofwater.
 10. The structured soy bean protein extrudate of claim 9,comprising 0.1-20 wt. % of fat.
 11. The structured soy bean proteinextrudate of claim 9, comprising 0.2-10 wt. % of fat.
 12. The structuredsoy bean protein extrudate of claim 9, infused with an aqueous liquid.13. The structured soy bean protein extrudate of claim 12, wherein theaqueous liquid is water comprising flavours.
 14. The structured soy beanprotein extrudate of claim 12, wherein the aqueous liquid is a broth.15. The structured soy bean protein extrudate of claim 9, wherein thestructured soy bean protein extrudate has a water-absorption capacity ofat least 50%.
 16. The structured soy bean protein extrudate of claim 9,wherein the denaturation temperature is at least 130° C.
 17. Astructured soy bean protein extrudate comprising: an extrudate from afibrous soy protein passing through an extruder at a temperature of atleast the boiling temperature of water into a first outside environment,thereby forming the structured soy bean protein extrudate havingenhanced porosity and/or randomization of fiber orientation relative toa fibrous protein composition cooled to below the boiling temperature ofwater, wherein the fibrous soy protein is obtained by subjecting a doughto shear forces and pressure in the extruder; the dough is obtained bydenaturing an aqueous soy protein composition by heating the aqueous soyprotein composition above a denaturation temperature of the aqueous soyprotein composition; and the aqueous soy protein composition has aprotein content based on dry matter of at least 15% by weight and below85% by weight.
 18. The structured soy bean protein extrudate of claim17, comprising 0.1-20 wt. % of fat.
 19. The structured soy bean proteinextrudate of claim 17, infused with an aqueous liquid.
 20. Thestructured soy bean protein extrudate of claim 19, wherein the aqueousliquid is one of water comprising flavours or a broth.
 21. Thestructured soy bean protein extrudate of claim 17, wherein thestructured soy bean protein extrudate has a water-absorption capacity ofat least 50%.
 22. The structured soy bean protein extrudate of claim 17,wherein the denaturation temperature is at least 130° C.